package lc20240702;

public class MinPathSum2 {
    public static int minPathSum(int[][] grid){
        if (grid == null || grid.length == 0 || grid[0].length == 0) {
            return 0;
        }

        int m = grid.length;
        int n = grid[0].length;
        int[][] dp = new int[m][n];

        dp[0][0] = grid[0][0];

        // 初始化第一行
        for (int j = 1; j < n; j++) {
            dp[0][j] = dp[0][j - 1] + grid[0][j];
        }

        // 初始化第一列
        for (int i = 1; i < m; i++) {
            dp[i][0] = dp[i - 1][0] + grid[i][0];
        }

        // 填充dp数组
        for (int i = 1; i < m; i++) {
            for (int j = 1; j < n; j++) {
                dp[i][j] = Math.min(dp[i - 1][j], dp[i][j - 1]) + grid[i][j];
            }
        }

        return dp[m - 1][n - 1];
    }

    public static void main(String[] args) {
        int[][] grid = {
                {1, 3, 1},
                {1, 5, 1},
                {4, 2, 1}
        };
        System.out.println(MinPathSum2.minPathSum(grid));
    }
}
